Interaction Between Polyethyleneimine and Zwitterionic Surfactant: Effect on Association Processes in Bulk and Deposition onto Solid Wafers

Abstract

[EN]Fluorescence probing and -potential measurements have been used to characterize the interactions in bulk between the zwitterionic surfactant 3-[(3-cholamidopropyl)-dimethyl-ammonium]- 1-propanesulphonate, CHAPS and the polymer polyethylene imine, PEI. Results show that the strongest attractive interactions are produced between the surfactant and the neutral form of the polymer PEI. Because the zwitterionic surfactant CHAPS has been proposed as component of biosensors, we are interested to study the effect of the polymer on CHAPS films, therefore we transfer the surfactant and PEI/CHAPS mixtures from the solution onto mica by using the Langmuir- Schaefer and dipping methodologies. The morphology of films is analyzed by means of Atomic force microscopy, AFM, Optical microscopy and Micro-Raman spectroscopy. The hydrodynamic flow of water after its evaporation induces the formation of ring-based structures not available to fabricate devices. This process predominates when materials are transferred from the solution onto mica by dipping. In contrast, the Langmuir-Schaefer films consist of spherical aggregates and the densest and the most ordered films were obtained by transferring the PEI/CHAPS mixture of surfactant concentration above the CMC.